I am using the internal wifi but the code suggested has fixed the
problem. I do not understand why the update stopped the wifi working
but all is fine now.

And from answering help center:-

Answers that do not fundamentally answer the question may be
removed. This includes answers that are:

commentary on the question or other answers

asking another, different question

“thanks!” or “me too!” responses

exact duplicates of other answers

barely more than a link to an external site

ot even a partial answer to the actual question

So what are the reasons to delete my answer ?

Now I getting more downvotes after answer re-opened. It seems like people here to downvote is because the question was not stated clearly although the answer given was useful.But
the funniest thing is the question has one vote although someone said that the question is unclear :D

I voted to undelete, and then downvoted, because there's no explanation as to why running these two commands would help. A "helpful" answer without explanation is more dangerous than helpful and deserves deletion.
– muruSep 20 '18 at 3:20

@muru I'm not expert in Ubuntu, but have tried to explain in my answer. Thanks for re-open the answer again.
– John JoeSep 20 '18 at 3:31

@muru so people downvote is because the question is not stated clearly even the answer is useful?
– John JoeSep 20 '18 at 6:14

Question title is much abroad than your problem.
– M.A.K. RiponSep 20 '18 at 9:47

3

Hey, you accepted Oli's answer below, but then you deleted your downvoted answer and reposted it verbatim. Where's the "working" you implicitly promised to show?
– ZannaSep 22 '18 at 5:58

@Zanna "Perhaps you miss to update wireless driver." That's my explanation. The code I suggested are used to make the wifi worked again.
– John JoeSep 22 '18 at 6:16

2 Answers
2

You didn't show your working

Imagine this... Your significant other gets severe abdominal pain. You take them to hospital. Without any discussion, they're immediately whisked away to surgery. No evidence the doctors actually investigated the problem. No explanation of what they think the problem is, or how surgery will fix it. How do you feel? Probably not great. And this is a scenario where you have some expectation that people are experts.

"Download this random file and essentially execute it run it as root." is not an acceptable answer without some basic explanation of:

What you think is going wrong

Why you think it'll help

We don't need paragraphs upon paragraphs, but in this case, you could expand the answer to include why this driver and why download/dpkg instead of apt.

If you can't offer that, you're shooting in the dark. Even if it did help this user, there's no scope around this, desperate random people with random wifi problems are going to run those random commands too. How do you know you're not doing them harm?

I feel you have accepted @Oli's answer but missed its point. So here's my attempt to point out what's wrong with your answer(s) posted to that question in particular.

A disclaimer first, I was the one to cast the first delete vote on your answer (10k+ users only) which you deleted again after it was undeleted. I admit I overlooked the comment by the original asker mentioning the answer worked for them. Otherwise I would've just downvoted with a comment explaining the reason behind it. I offer my sincere apologies for that. But you did the right thing by bringing it up here at meta after the answer was deleted. I shall try my best to be as objective as I can be with my analysis.

Now to the issues with the question and your answers. First of all, the question itself is not very clear. It says Wi-Fi stopped working after Ubuntu 16.04 updates, but

says nothing about the nature of the update(s) (only "the updates that I received this morning")

more importantly says nothing about the kernel version and the wireless device & driver being used (only laptop model is mentioned: HP Stream11)

Then your answer is essentially getting a specific version of the bcmwl-kernel-source package and installing it. But why do you think it would work when we don't even know which device OP is using? We cannot even tell whether OP has a Broadcom device at all.

It is not very wise to assume the device from the laptop model itself as laptop manufacturers may produce same model with different parts by different part-manufacturers depending on the model-variation, region, batch etc. In fact HP apparently ships (at least some variations of) Stream 11 laptops with Realtek RTL8723BE device instead of any Broadcom device too.

So your answer looked to me like a random shot in the dark which thankfully worked out for OP in this case (If I'm not horribly mistaken you have posted nearly identical answers to other questions which got deleted). Now imagine someone with the same laptop with a different device, but a similar-looking issue may find your answer and blindly install that specific package which most likely waste their time and energy and may cause breakage in cases (running random commands with root privilege is not a wise thing in general). As @Andrew T. puts it (in a comment posted under the deleted answer)

[...] the purpose of Stack Exchange is to build a high quality repository of Q&A as mentioned on the tour, so the goal is not only to help OP and yourself, but also future readers. Like, what is "bcmwl-kernel-source" and why it fixes the issue, etc. because this might fix OP's issue, but not other readers for this same problem.

You have had enough reputation to post a comment under the question and ask OP for more info. Alternatively, you could have added some explanation (or a caveat) to your answer following Oli's suggestion:

What you think is going wrong

Why you think it'll help

For example you could've added something like

If your Stream 11 comes with Broadcom <insert-device-ID> chip, then recent update of the <insert-package-name> may have broken <insert-something>. To fix this install the <insert-package-name-and-version> package by running the following commands:
.
.

In this case the onus would be on the future reader before trying the solution as you have mentioned clearly in which case your solution is supposed to work.